Binary pattern matching

Binaries are contiguous byte sequences. Pattern-match them with <<>>: <<b1, b2, rest::binary>> = <<1, 2, 3, 4>> binds the first two bytes and the remainder.

Specify width with size: <<n::size(16)>> matches 16 bits. Default integer segments are unsigned big-endian. Use unit:8 when you want size counted in bytes.

UTF-8 code points use utf8: <<c::utf8, rest::binary>> = "Ábc" binds the first code point. A binary (or bytes) rest segment matches remaining bytes.

Construct binaries the same way: <<1, 2, "hi"::utf8>>. Strings are UTF-8 binaries, so binary patterns apply to "..." values when the shape fits.

Misses: treating <<a, b>> like a tuple {a, b}, forgetting ::binary for a rest segment, or matching utf8 against arbitrary non-UTF-8 bytes.

<<b1, b2, rest::binary>> = <<1, 2, 3, 4>>
<<n::size(16)>> = <<0, 7>>
<<c::utf8, _::binary>> = "Áx"
IO.inspect({b1, b2, rest, n, c})